Move partial unmap handler to the native signal handler (#3437)

* Initial commit with a lot of testing stuff.

* Partial Unmap Cleanup Part 1

* Fix some minor issues, hopefully windows tests.

* Disable partial unmap tests on macos for now

Weird issue.

* Goodbye magic number

* Add COMPlus_EnableAlternateStackCheck for tests

`COMPlus_EnableAlternateStackCheck` is needed for NullReferenceException handling to work on linux after registering the signal handler, due to how dotnet registers its own signal handler.

* Address some feedback

* Force retry when memory is mapped in memory tracking

This case existed before, but returning `false` no longer retries, so it would crash immediately after unprotecting the memory... Now, we return `true` to deliberately retry.

This case existed before (was just broken by this change) and I don't really want to look into fixing the issue right now. Technically, this means that on guest code partial unmaps will retry _due to this_ rather than hitting the handler. I don't expect this to cause any issues.

This should fix random crashes in Xenoblade Chronicles 2.

* Use IsRangeMapped

* Suppress MockMemoryManager.UnmapEvent warning

This event is not signalled by the mock memory manager.

* Remove 4kb mapping

2 files changed, 29 insertions, 8 deletions

diff --git a/Ryujinx.Cpu/Jit/MemoryManagerHostMapped.cs b/Ryujinx.Cpu/Jit/MemoryManagerHostMapped.cs
index 5961e377..4df29699 100644
--- a/Ryujinx.Cpu/Jit/MemoryManagerHostMapped.cs
+++ b/Ryujinx.Cpu/Jit/MemoryManagerHostMapped.cs
@@ -89,10 +89,10 @@ namespace Ryujinx.Cpu.Jit
             MemoryAllocationFlags asFlags = MemoryAllocationFlags.Reserve | MemoryAllocationFlags.ViewCompatible;
 
             _addressSpace = new MemoryBlock(asSize, asFlags);
-            _addressSpaceMirror = new MemoryBlock(asSize, asFlags | MemoryAllocationFlags.ForceWindows4KBViewMapping);
+            _addressSpaceMirror = new MemoryBlock(asSize, asFlags);
 
             Tracking = new MemoryTracking(this, PageSize, invalidAccessHandler);
-            _memoryEh = new MemoryEhMeilleure(_addressSpace, Tracking);
+            _memoryEh = new MemoryEhMeilleure(_addressSpace, _addressSpaceMirror, Tracking);
         }
 
         /// <summary>
diff --git a/Ryujinx.Cpu/MemoryEhMeilleure.cs b/Ryujinx.Cpu/MemoryEhMeilleure.cs
index a8229581..806ef811 100644
--- a/Ryujinx.Cpu/MemoryEhMeilleure.cs
+++ b/Ryujinx.Cpu/MemoryEhMeilleure.cs
@@ -6,36 +6,57 @@ using System.Runtime.InteropServices;
 
 namespace Ryujinx.Cpu
 {
-    class MemoryEhMeilleure : IDisposable
+    public class MemoryEhMeilleure : IDisposable
     {
         private delegate bool TrackingEventDelegate(ulong address, ulong size, bool write, bool precise = false);
 
-        private readonly MemoryBlock _addressSpace;
         private readonly MemoryTracking _tracking;
         private readonly TrackingEventDelegate _trackingEvent;
 
         private readonly ulong _baseAddress;
+        private readonly ulong _mirrorAddress;
 
-        public MemoryEhMeilleure(MemoryBlock addressSpace, MemoryTracking tracking)
+        public MemoryEhMeilleure(MemoryBlock addressSpace, MemoryBlock addressSpaceMirror, MemoryTracking tracking)
         {
-            _addressSpace = addressSpace;
             _tracking = tracking;
 
-            _baseAddress = (ulong)_addressSpace.Pointer;
+            _baseAddress = (ulong)addressSpace.Pointer;
             ulong endAddress = _baseAddress + addressSpace.Size;
 
-            _trackingEvent = new TrackingEventDelegate(tracking.VirtualMemoryEventEh);
+            _trackingEvent = new TrackingEventDelegate(tracking.VirtualMemoryEvent);
             bool added = NativeSignalHandler.AddTrackedRegion((nuint)_baseAddress, (nuint)endAddress, Marshal.GetFunctionPointerForDelegate(_trackingEvent));
 
             if (!added)
             {
                 throw new InvalidOperationException("Number of allowed tracked regions exceeded.");
             }
+
+            if (OperatingSystem.IsWindows())
+            {
+                // Add a tracking event with no signal handler for the mirror on Windows.
+                // The native handler has its own code to check for the partial overlap race when regions are protected by accident,
+                // and when there is no signal handler present.
+
+                _mirrorAddress = (ulong)addressSpaceMirror.Pointer;
+                ulong endAddressMirror = _mirrorAddress + addressSpace.Size;
+
+                bool addedMirror = NativeSignalHandler.AddTrackedRegion((nuint)_mirrorAddress, (nuint)endAddressMirror, IntPtr.Zero);
+
+                if (!addedMirror)
+                {
+                    throw new InvalidOperationException("Number of allowed tracked regions exceeded.");
+                }
+            }
         }
 
         public void Dispose()
         {
             NativeSignalHandler.RemoveTrackedRegion((nuint)_baseAddress);
+
+            if (_mirrorAddress != 0)
+            {
+                NativeSignalHandler.RemoveTrackedRegion((nuint)_mirrorAddress);
+            }
         }
     }
 }